Method of producing mica insulators for spark-plugs



A. R. MOSLER AND G. MARGOLIN.

METHOD OF PRODUCING MICA INSULATOHS FOR SPARK PLUGS APPLICATION FILED JAN. 26. 1918.

1,320,638, v PatentedNo .4,1919.'

' vwewfoza mart ears are are ARTHUR. R. MOSLER AND GEORGE MARG-OLIN, OF NEW YORK, N.Y., ASSIGLIORS TO A. R.

MOSLER & 00., OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

METHOD OF PRDDUCING MICA INSULATORS FOR SPARK-PLUGS.

Specification of Letters Patent.

Patented Nov. a, 1919.

Application filed January 26, 1918. Serial No. 214,024.

Spark-Plugs, of which the following is a specification.

In the manufacture of mica insulators for spark plugs, it has been customary to subject the stack of mica disks to pressure'while in their dry state to compress them as much as possible.

By this method it was impossible to produce uniform insulators and to prevent leakage when the insulators were in use. The reasons for this were that it was impossible to sufliciently compress the disks to eliminate the air pockets between the laminae and that it was also impossible to secure a maximum and uniform compression because the disks were uneven and were not free to turn one on another to properly seat themselves as they were being compressed.

The method above described was also very expensive as it was practically impossible for the operator to rightly judge the number of uncompressed mica disks which would be needed to compress to a redetermined length of insulator, thus entailing the time and trouble of removing the pressure means and adding or subtracting the disks as. might be necessary to produce the length desired. The mica insulators were, therefore, unsatisfactory because of their lack of uniformity, leakage and consequent inefficiency, short life and expense by reason of the number of operations involved.

The object of our inventionis to overcome the faults above enumerated and to produce,

in a very simple and inexpensive'manner, uniform, highly compressed, non-leakable mica insulators. This is obtained by first wetting the stack of disks, com ressing them while wet, and drying the dis s while compressed to form a unitary body, from which an insulator of the desired length may be severed. We have discovered that by wetting the disks, the stacks may be compressed to a much greater degree than heretofore and that the disks will properly seat themselves, thus obtaining greater uniformity as well as greater density.

In the accompanying drawings,

Figure 1 is a diagrammatic View showing the step of wetting the mica disks while mounted on their core rod, Fig. 2 is a view partly in side elevation and partly in section of apress with a stack of wet uncompressed mica disks in position therein ready to be compressed,

Fig. 3 is'an end view of the same,

Fig. 4 is a section taken in the plane of the line IVIV of Fig. 2, 1

Fig. 5 is a view similar to Fig. 2, after the stack has been compressed and the core rod removed,

Fig. 6 is a side view of the insulator stack after it has been pressed into a unitary bod and dried, and

Fig. 7 is a view of an insulator of the desired length severed from the stack.

In producing our improved mica insulator, the mica disks are first wet. In the present instance, the disks are wet with a volatile liquid, such, for instance, as alcohol. This may be accomplished by stringing the disks on their core rod 1 and submerging the same in a suitable tank 2 containin the liquid 3. The stack of disks is then pIaced in a suitable press and the desired endwise pressure is exerted on the said stack. This press may be of any suitable construction. In the present instance we have shown a press comprising the end plates 4, 5, the intermediate oppositely arranged V-shaped troughs 6, 7, for engaging the periphery of the stack and the hollow pressure screws 8,

1 screws 8, 9, have heads 10, 11, fitted to the ends of the stack within the troughs 6, 7 The troughs 6, 7, have screw threaded lugs 12 projecting through the plates 1, 5, and nuts 13 engage said screw threaded lugs exterior to the plates to hold the plates and troughs in assembled adjustment.

After the stack of disks has. been compressed, the core bar 1 is removed and the stack of disks while still under compression is dried, as, for instance, by placing the press in an oven with a comparatively low heat. This oven is not shown in the accompanying drawings, as it is obvious that any suitable means may be employed for drying the stack. After the compressed stack has been dried, it is removed from the press and an insulator of the desired length may be severed therefrom. lhis insulator Will be a unitary body of great density and will be suitable for use in spark plugs exposed to extreme heat and pressure.

We have found that in compressing the disks while wet, that they not only compress to a considerably greater degree than when dry but that also they have a tendency to turn one upon another to properly seat themselves thus eliminating the chances of leaving air pockets and other leakage points in the stack.

What We claim is 1. The method of producing mica insulators for spark plugs consisting in Wetting mica disks with a volatile liquid, such for instance as alcohol, compressing the disks while Wet, drying the same While compressed, to form a unitary body, and severing therefrom the length desired for the insulator.

2. The method of producing mica insulators for spark plugs, consisting in stringing on a core rod, more disks than are needed for the insulator length desired, submerging the same in a tank of volatile liquid, such for. instance as alcohol, removing the stack from the tank, subjecting the stack to great endWise pressure, removing the core rod, drying the stack at a low heat while compressed, to form a unitary body, removing the pressure, and severing from the stack the length desired for the insulator.

In testimony, that We claim the foregoing as our invention, we have signed our names, this 10th day of January 1918.

ARTHUR R. MOSLER. GEORGE MARGOLIN, 

